1. Field of the Invention
This disclosure relates generally to a sensor holder for a medical sensor.
2. Description of Related Art
Information on the amount of oxygen within blood or more preferably a blood flow is desirable in many instances. This is often characterized as the oxygen content or oxygen saturation of the blood. Oximeters are able to provide this type of information and are generally well known in the art. Patient data that is used by the oximeter to determine the oxygen content/saturation is monitored/measured by an oximeter sensor that operatively interfaces with the oximeter.
Oximeter sensors typically employ a pair of light sources that emit light at different wavelengths, as well as one or more optical detectors. Electrical signals are provided by the oximeter to the oximeter sensor to operate the light sources in a predetermined manner (e.g., each light source is “pulsed” in accordance with a predetermined pattern). Light from each of the light sources will either be absorbed by the blood or will pass entirely through the patient's tissue and blood for receipt by the detector(s). Electrical signals from the detector(s) are provided back to the oximeter. Information on how the light sources are being operated, the wavelengths of these two light sources, and the amount of light, which passes through the blood to the detector(s) are all used by the oximeter to calculate the oxygen content/saturation of the blood. This information will then typically be displayed for review by appropriate personnel.
Various factors contribute to the overall success of a given oximeter sensor holder. One is its comfort when positioned on the relevant body part. It would be desirable to have an oximeter sensor holder that provided at least a certain degree of a patient comfort and would not cause breakdown of the patient's skin when worn for long periods of time. Enhanced patient comfort can be realized by things such as the size, shape, and weight of the oximeter sensor holder, as well as having the oximeter sensor holder interface with the patient so as to at least reduce the potential for the development of “pressure points.” Uneven distribution of the forces being exerted on the patient by the oximeter sensor holder can contribute to the development of undesired soreness and possibly pressure necrosis on the patient's skin surface.
Another well-known discomfort is the sweating of the relevant body part. More closed the sensor holder structure is more sweating it can cause and thus at least the patients that are conscious tend to cool the finger themselves that causes measurement stops. Also excessive sweating increases the need for cleaning.
Being a reusable oximeter sensor, one of the biggest challenge together with the comfort, is the durability of the sensor holder. The known mechanical failure in the oximeter sensor holders is the wire breakage that may occur when the cable is repeatedly bent relative to the sensor holder. If the oximeter sensor holder is designed to separate the single wires inside the cable right after the point where the flex relief integrates to the sensor holder, there will be a point of mechanical discontinuance that may lead to the described breakage.
There are a number of competing design considerations for oximeter sensor holders. First, the sensor holders should have the ability to achieve a reliable interface between the emitter and detector in the sensor holder and the patient's skin. Second, the oximeter sensor holder should be adapted for ready application and removal from the patient with a minimal amount of pair or discomfort for the patient. Finally, the oximeter sensor holder should provide a gentle interface with the patient's skin.
There are various means for holding the emitter(s)/detector in contact to a patient's tissue; however, two common types are flexible and clip-type sensor holders. Many currently available clip-type sensor holders have a hard shell, which has a high profile and is maintained on the finger by the action of a spring. Since excess pressure on the finger can dampen or eliminate the pulsation in the blood supply to the finger, these springs are intentionally relatively weak. The result of this compromise is that the spring-held sensor holders readily fall off the finger. It is desirable for a finger sensor holder to be retained on the finger with only slight pressure, while at the same time being immune to easy dislocation. Also accommodation on the different sizes of the finger is challenging to achieve with a sensor holder having hinge(s). Flexible sensor holders may simply comprise an elastic holder onto which the emitter(s)/detector are mounted for placement about a patient appendage.
There are known sensor holder designs that are designed to provide an evenly distributed pressure around the finger. However no sensor holder has been designed equal to the shape of a human finger. The ones closest to finger shape design do not distribute pressure evenly around the finger. Also majority of the known sensor holder designs are closed structures, so that only the proximal and distal ends are open, causing easily sweating and moisture between the sensor holder and finger. The few sensor holder designs that introduce holes or openings on the sensor holder between both ends have a high possibility to create pressure points on the edges of the openings that lay against the finger. Also the openings are not cooling the skin elsewhere, than just on the opening area as there are no air circulation between those openings and proximal/distal ends.